For the home winemaker there is no reason to worry about whether Sodium or Potassium is the preferred legal entity to use. Both are completely safe and the reason Potassium is preferred is that wine is considered to be a low sodium food. Avoiding the addition of any sodium salt keeps it that way. But the amount of sodium in the few ppm of sodium bisulfite you'll add is probably always inconsequential. Sodium is cheaper and won't screw up the stability of the wine if you add it. Potassium is much more expensive and, if a lot is added, can (at least in theory) cause a stable wine to become cold unstable. After adding a potassium salt like metabisulfite you'd have to re-chill the wine to get the extra potassium bitartrate to drop out and make the wine stable again. As a practical matter, you're not likely to add enough potassium metabisulfite to cause stability problems. Similarly, if you add sodium bisulfite, you're not likely to add enough sodium to make any difference to the low sodium status of your wine. All in all, I think you should use the cheapest and easiest (namely, sodium bisulfite) for your wine. Be sure to calculate the amount of actual SO2 and not the total salt you're adding. Hope this helps. Dick Peterson

For those who don't recognize the name...our friend just received advice from one of America's most highly regarded winemakers. His profile humbly lists him as "enologist." Not untrue, but this enologist worked in research at Gallo, alongside the late Andre Tchelistcheff at Beaulieu, was founding partner and winemaker at The Monterey Vineyard, ditto for Atlas Peak and is now a major partner in Napa's Folie a Deux...and I've probably left out a bunch of stuff.